摘要：

为明确抗病次生代谢物香豆素对核桃炭疽病生防菌枯草芽孢杆菌 B2菌株的协同抗病机制,通过外源添加不同浓度香豆素测定其对枯草芽孢杆菌B2菌株生长、生物膜形成和定殖能力的影响。采用香豆素0.001(XD-1),0.010(XD-2),0.100(XD-3),1.000(XD-4),2.000 mmol/L(XD-5)5个处理,测定了不同浓度对枯草芽孢杆菌B2菌株生长的影响;观察生物膜形成情况并采用称质量法和结晶紫染色法对生物膜形成能力进行定量测定;通过涂布平板法测定荧光标记枯草芽孢杆菌B2菌株的定殖情况。结果表明,不同浓度香豆素均会促进菌株生长,0.100 mmol/L香豆素处理较对照差异显著,2.000 mmol/L香豆素处理与对照无显著差异;0.100 mmol/L香豆素处理显著强化生物膜的褶皱和立体程度,同时,镜检结果也显示,该处理的生物膜细胞显著聚集在一起;对生物膜的定量结果表明,0.100 mmol/L香豆素处理的生物膜形成能力最强;此外,香豆素可提高B2菌株的叶际定殖能力,定殖量在培养7 d达到顶峰,且0.100 mmol/L处理显著增加菌株叶际定殖数量。综上所述,本研究揭示了香豆素在调控枯草芽孢杆菌B2菌株对核桃炭疽病的生物防治效果方面的重要作用,高效发挥生防菌的生防潜力,为核桃炭疽病的生物防治提供了一种有效的策略。

关键词: 枯草芽孢杆菌, 香豆素, 生物膜, 定殖

Abstract:

In order to identify the synergistic mechanism of disease resistance of secondary metabolite coumarin to Bacillus subtilis B2,the biological control bacterium of walnut anthrax,this study measured the effects of different concentrations of coumarin on the growth,biofilm formation and colonization ability of B.subtilis B2.Coumarin was treated with 0.001(XD-1),0.010(XD-2),0.100(XD-3),1.000(XD-4),2.000 mmol/L (XD-5),and the effects of different concentrations on the growth of B.subtilis B2 strain were determined.The biofilm formation was observed and the biofilm formation ability was quantitatively determined by weighing method and crystal violet staining method.Colonization of the fluorescently labeled B.subtilis B2 strain was determined by coating plate method.The results showed that different concentrations of coumarin could promote the growth of the strains,0.100 mmol/L coumarin treatment was significantly different from the control,2.000 mmol/L coumarin treatment was not significantly different from the control.The 0.100 mmol/L coumarin treatment significantly enhanced the folding and stereoscopic degree of the biofilm,and the microscopic results also showed that the biofilm cells were significantly clustered together.The quantitative results of biofilm showed that 0.100 mmol/L coumarin treatment had the strongest biofilm formation ability.In addition,coumarin could improve the interfoliar colonization ability of strain B2,and the colonization amount reached the peak at 7 days after culture,and the 0.100 mmol/L treatment significantly increased the interfoliar colonization number of strain B2.In summary,this study revealed the important role of coumarin in regulating the biocontrol effect of B.subtilis B2 strain on walnut anthracnose,and gave full play to the biocontrol potential of biocontrol bacteria,providing an effective strategy for the biocontrol of walnut anthracnose.

Key words: Bacillus subtilis, Coumarin, Biofilm, Colonization